The invention relates to a communication system comprising a station for charge metering of a connection point and to terminal units connected to connection points coupled to the station.
In many communication systems it is often not guaranteed that only the authorized subscriber can communicate with other subscribers via his terminal unit. It is possible, for example, that unauthorized connection lines between a terminal unit of the authorized subscriber and the station, which forms, for example, part of a telephone exchange, are manipulated. This damages both the subscriber and the operating company of the network.